The invention relates to genetically modifying trees through manipulation of the lignin biosynthesis pathway, and more particularly, to genetically modifying trees through the down regulation of p-coumarate Co-enzyme A ligase (CCL) to achieve faster growth, and/or altered lignin content, and/or altered lignin structure, and/or altered cellulose content and/or disease resistance of the trees and to the use of promoters of the CCL genes to drive gene expression specifically in xylem tissue or specifically in epidermal tissues.
Genetic engineering of forest tree species to conform to desired traits has shifted the emphasis in forest tree improvement away from the traditional breeding programs during the past decade. Although research on genetic engineering of forest trees has been vigorous, the progress has been slow due.
The ability to make trees grow faster and be disease resistant to produce the highest volume of wood in the shortest period of time has been and continues to be the top objective of many forest products company worldwide. The ability to genetically increase the optimal growth of trees would be a commercially significant improvement. Faster growing trees could be used by all sectors of the forest and wood products industry worldwide.
Lignin, a complex phenolic polymer, is a major component in cell walls of secondary xylem. In general, lignin constitutes 25% of the dry weight of the wood, making it the second most abundant organic compound on earth after cellulose. Although lignin plays an important role in plants, it usually represents an obstacle to utilizing biomass in several applications. For example, in woodpulp production, lignin has to be removed through expensive and polluting processes in order to recover cellulose.
Thus, it is desirable to genetically engineer plants with reduced lignin content and/or altered lignin composition that can be utilized more efficiently. Trees that could be genetically engineered with a reduced amount of lignin would be commercially valuable. These genetically engineered trees would be less expensive to pulp because, in essence, part of the pulping has already been performed due to the reduced amount of lignin.
Trees with increased cellulose content would also be commercially valuable to the pulp and paper industry.
Disease resistance in plants is also a most desirable plant trait. The impact of disease resistance in trees on the economy of forest products industry worldwide is significant.
Promoters that target specific plant tissue could be useful in manipulating gene expression to enable the engineering of traits of interest in specific tissue of plants, such as, xylem and epidermal tissues.
Although studies have revealed several general properties of plant p-coumarate Co-enzyme A ligase (CCL), the role of CCL in regulating the synthesis of monolignols in response to different states of development and environmental stress in tree species remains largely unknown. Furthermore, multiple CCL isoforms are normally present in plants, channeling phenolic compounds to the biosynthesis of not only lignin but also other phenylpropanoids, such as flavonoids. Since CCL isoforms have not been previously cloned from tree species for the identification of their biochemical functions, the presence of CCL isoforms remains so far as a challenge to a specific control of metabolic flux to the lignin biosynthesis in tree species.
The invention provides a method to genetically alter trees through the down regulation of p-coumarate Co-enzyme A ligase (CCL). Such down regulation of CCL results in faster growth, and/or reduced lignin content, and/or altered lignin structure, and/or altered cellulose content and/or disease resistance. The invention also provides for genetically engineered trees which have been altered to down regulate p-coumarate Co-enzyme A ligase (CCL) to achieve faster growth, and/or reduced lignin content, and/or altered lignin structure, and/or increased cellulose content and/or increased disease resistance. The invention also provides tissue specific promoters of the CCL genes that can be used to manipulate gene expression in target tissue such as xylem and epidermal tissues.
It is one object of the present invention to down regulate p-coumarate Co-enzyme A ligase (CCL) in trees.
It is another object of the present invention to provide a method to genetically alter trees to grow faster.
It is another object of the present invention to provide a method to genetically alter the growth of trees through manipulation the lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to provide genetically altered trees with an accelerated growth characteristic.
It is another object of the present invention to provide transgenic trees with an accelerated growth characteristic which have been genetically altered by down regulating lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to provide a method to genetically alter trees to reduce their lignin content.
It is another object of the present invention to provide a method to genetically alter the lignin content of trees through manipulation of a lignin pathway enzyme.
It is another object of the present invention to genetically engineer trees which have reduced lignin content through manipulation of lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to provide genetically altered trees with a reduced lignin content.
It is another object of the present invention to provide transgenic trees with reduced lignin content which have been genetically altered by down regulating the p-coumarate Co-enzyme A ligase (CCL).
It is another object of the present invention to provide a method to genetically alter trees to change their lignin structure through manipulation of lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to provide trees with altered lignin structure.
It is another object of the present invention to provide a method to increase the cellulose content in trees.
It is another object of the present invention to provide a method to increase the cellulose content of trees through the manipulation of a lignin pathway enzyme.
It is another object of the present invention to provide trees with increased cellulose content.
It is another object of the present invention to provide transgenic trees having increased cellulose content from the down regulation of CCL.
It is another object of the present invention to provide a method to genetically alter trees to increase their disease resistance.
It is another object of the present invention to provide a method to genetically alter trees to be more disease resistant through manipulation of the lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to genetically alter trees to increase their disease resistance to fungal pathogens.
It is another object of the present invention to provide trees with increased disease resistance.
It is another object of the present invention to provide transgenic trees with increased disease resistance through down regulation of the lignin pathway p-coumarate Co-enzyme A ligase.
It is another object of the present invention to provide a method using a promoter of a CCL gene to target gene expression in specific plant tissue.
It is another object of the present invention to provide a method using a promoter of a CCL gene to target gene expression specifically in plant xylem.
It is another object of the present invention to provide a method using a promoter of the CCL gene to target gene expression specifically in the epidermal tissues of plants.
It is another object of the present invention to provide a CCL gene promoter that targets gene expression specifically in the xylem of plants.
It is another object of the present invention to provide a CCL gene promoter that targets gene expression specifically in the epidermal tissues of plants.
Other features and advantages of the invention will become apparent to those of ordinary skill in the art upon review of the following drawing, detailed description and claims.